The invention generally relates to electrical switches and more particularly related to an actuating element for an electrical switch.
In general, in order to create a pivotable support for an actuating element of an electrical switch, support-axis stubs are formed perpendicularly to its direction of rotation, these stubs being opposably arranged on the switch and being inserted in corresponding housing recesses. However, the support-axis stubs are relatively prone to break, for which reason a reject can be generated if the actuating element is improperly mounted in the housing. If several such actuating elements are to be housed in a common housing, a corresponding number of support sites must be realized, at a significant manufacturing expense.
The direct connection of an actuating element to a housing via the intermediary of a film hinge is difficult in that the material for the housing must have different material properties from the material suitable for a strip of film. This problem cannot be solved by manufacture in a two-component injection molding process, since the different materials no longer combine sufficiently homogeneously in this process.
An actuating element for an electrical switch pivotably supported on a partition via a film hinge is known from U.S. Pat. No. 4,689,455 A. The partition is connected in a latching manner to a housing of the switch, and is aligned parallel to a housing wall. The actuating element and the partition are set into a recess of the housing.
Moreover, JP 06 290680 A (Patent Abstracts of Japan, Vol. 1995, No. 1, Feb. 28, 1995) discloses an actuating element for a switch, which actuating element is connected via a hinge to a partition associated with a housing wall. The housing wall has no guides for the partition.
Furthermore, an electrical pushbutton switch with an actuating element, pivotably supported on a housing, for applying pressure to a switching contact is known from EP 0 887 819 A2. A pushbutton support is provided for the pivotable support of each actuating element, said support consisting of at least one support bracket, with support pins, fixed to the housing, and of a corresponding flange hole located in a side wall of the actuating element.
The invention addresses the problem of creating an actuating element of the type initially cited that has a small number of individual parts, is mechanically robust, and in addition, is simple and economical to produce and mount.
The invention solves this problem in that a film hinge is provided as the hinge, said film hinge connecting the actuating element to a partition engaged with the housing, said partition covering the associated housing wall of the outside and being guided on the latter, and in that at least one stop arm is formed on the underside of the actuating element, said arm extending behind a projection formed on the housing wall opposite the film hinge.
As a consequence of this measure, it is not necessary to provide additional structural components for pivotable support of the actuating element. As a consequence of connecting the actuating element to the partition, it is possible to manufacture this partition from a suitable plastic upon which mechanical demands can be placed that differ in comparison to the material of the housing. For example, a plastic reinforced with glass fibers with high strength is used to manufacture the housing, said plastic not being usable in a film hinge and the visible surface of the actuating element. The actuating element is produced, with the film hinge and the relatively lightly loaded partition, from a non-reinforced plastic that assures the necessary elasticity and a high surface quality necessary for the visible surfaces of the actuating element. Relatively rapid assembly is assured in that the partition can be engaged with the housing. When the partition is arranged paralled to a housing wall, an increased stability of the housing is achieved. Furthermore, connection to a housing of differently-formed actuating elements is possible after an appropriate change of the die mole, so that given a design change, only the actuating elements are adapted while the housing and the switch parts inserted in it are kept the same. As a consequence of the guidance of the partition on the associated housing wall, positional fixation between the housing and the actuating element is assured. In order to prevent the actuating element from pivoting counter to the direction in which it is pressed, at least one stop arm is formed on the underside of the actuating element, said arm extending behind a projection formed on the housing wall opposite the film hinge
The guide is advantageously designed as a dovetail guide. The dovetail guide assures guidance in two axes, and accordingly provides precise positioning of the actuating element in relation of the housing.
Several spaced-apart guide ridges of the housing wall, and corresponding guide grooves in the partition, are preferably provided. The guide ridges extend over approximately the entire height of the housing wall, and the guide grooves extend over approximately the entire height of the partition. Rotation of the partition relative to the housing wall is practically excluded by the relatively great lengths of the guides and their spacing apart from each other.
According to an advantageous further development of the concept of the invention several actuating elements are arranged parallel to each other perpendicularly to the longitudinal axis of the housing, those actuating elements each being connected to the partition via at least one film hinge. As a result, several switching functions are integrated into one housing; of course, a separate switching contact to be pressed is associated with each of the actuating elements.
Since the film hinge on the visible side of the actuating element is considered objectionable on visual and tactile grounds, the partition extends into the film hinge and an actuating surface of the actuating element extends substantially perpendicularly from the partition and/or the film hinge. The film hinge is thereby associated with the outermost edge area of the actuating element.
The one end face of the actuating element is preferably aligned flush with the partition and the associated film hinge, and the other end face preferably extends over part of the housing wall opposite the partition. Thus, the entire housing surface and the film hinges are covered by the actuating element or elements.
In order to effectively prevent the partition with the actuating element from being pulled off of the housing, at least one clip arm with a clip opening for latching reception of a clip projection formed on the housing wall is advantageously designed in the partition.
According to a further embodiment, perforated projections for attachment between spokes of a steering wheel are provided on a base of the housing, said base holding the switching contacts designed as a microswitch. The entire switch, which can be used, e.g., to control a Tempomat, is reliably connected to the steering wheel via the holes by screws.
In order to adapt the geometry of the housing to the installation situation on a steering wheel, the cross section of the housing is advantageously designed in a substantially triangular shape, in which the housing walls of the longitudinal sides form the sides of the triangle, an end face housing wall forms the base, and the other end face housing wall essentially forms an arcuate connection of the longitudinal-side housing walls.
The free end faces of the actuating elements opposite the film hinges are advantageously designed in an arc. In this manner, even the actuating elements are adapted to the contour of the steering wheel.
The switching contacts are relatively sensitive components that must be protected from being overloaded by too great a force when the actuating elements are pressed. Therefore, a stop is advantageously associated with each actuating element on the side opposite the film hinge, said stop coming to rest against the end face of the corresponding housing wall upon being pressed.
In order to convert the pivoting movement of the actuating element into a straight-line movement for applying pressure to the microswitch associated with it, a push rod associated with each actuating element for applying pressure to the corresponding microswitch is movably arranged, preferably on one of the housing walls of the longitudinal sides.
Of course, the previously cited features still to be explained in the following can be used not only in the particular combination indicated, but also in other combinations without departing from the scope of the present invention.
The invention is explained in the following using an exemplary embodiment and making reference to the associated drawings.